Effect of seeding technique and scaffold material on bone formation in tissue‐engineered constructs

Abstract

The aim of the present study was to test the hypothesis that both scaffold material and the type of cell culturing contribute to the results of in vivo osteogenesis in tissue-engineered constructs in an interactive manner. CaCO3 scaffolds and mineralized collagen scaffolds were seeded with human trabecular bone cells at a density of 5 x 10(6) cells/cm(3) and were left to attach under standard conditions for 24 h. Subsequently, they were submitted to static and dynamic culturing for 14 days (groups III and IV, respectively). Dynamic culturing was carried out in a continuous flow perfusion bioreactor. Empty scaffolds and scaffolds that were seeded with cells and kept under standard conditions for 24 h served as controls (groups I and II, respectively). Five scaffolds of each biomaterial and from each group were implanted into the gluteal muscles of rnu rats for 6 weeks. Osteogenesis was assessed quantitatively by histomorphometry and expression of osteocalcin (OC) and vascular endothelial growth factor (VEGF) was determined by immunohistochemistry. CaCO3 scaffolds exhibited 15.8% (SD 3.1) of newly formed bone after static culture and 22.4% (SD 8.2) after dynamic culture. Empty control scaffolds did not show bone formation, and scaffolds after 24 h of standard conditions produced 8.2% of newly formed bone (SD 4.0). Differences between the controls and the scaffolds cultured for 14 days were significant, but there was no significant difference between static and dynamic culturing. Mineralized collagen scaffolds did not show bone formation in any group. There was a significant difference in the expression of OC within the scaffolds submitted to static versus dynamic culturing in the CaCO3 scaffolds. VEGF expression did not show significant differences between static and dynamic culturing in the two biomaterials tested. It is concluded that within the limitations of the study the type of biomaterial had the dominant effect on in vivo bone formation in small tissue-engineered scaffolds. The culture period additionally affected the amount of bone formed, whereas the type of culturing may have had a positive effect on the expression of osteogenic markers but not on the quantity of bone formation.

The Evaluation of Mineralized Collagen as a Carrier for the Osteoinductive Material COLLOSS®E, In Vivo

“…Another four studies evaluated mineralized collagen in in vivo studies, in which two experimental groups were tested in ectopic sites and three in orthotopic sites. [16][17][18][19] The results in ectopic sites are similar to our current findings, as they, indeed, report inflammatory reaction, resulting in complete phagocytosis of the collagen without any signs of bone formation. 17,18 The results in orthotopic sites are inconsistent.…”

“…[16][17][18][19] The results in ectopic sites are similar to our current findings, as they, indeed, report inflammatory reaction, resulting in complete phagocytosis of the collagen without any signs of bone formation. 17,18 The results in orthotopic sites are inconsistent. Schliephake et al 19 reported no enhancement of bone formation by mineralized collagen, when implanted in rat mandibles.…”

Bone formation in trabecular bone cell seeded scaffolds used for reconstruction of the rat mandible

“…A previous study with two of the three scaffold materials, using human trabecular bone cells derived and treated in the same way and seeded under identical seeding density and culturing conditions, showed bone formation after transplantation to ectopic sites. Bone formation in that study was strongly dependent on the scaffold material, because the cells produced considerable amounts of bone in CaCO 3 scaffolds but no bone formation was found in the mineralized collagen scaffolds 29 . The present study appears to contradict these results, in that none of the seeded scaffold materials had a positive effect on bone formation when implanted into non-healing defects in rat mandibles.…”

Bioreactor Systems for Human Bone Tissue Engineering

“…In 2009, Schliephake et al cultured constructs of human trabecular bone cells and CaCO 3 scaffolds (pore size: 250-750 µm) or mineralized collagen scaffolds (pore size: 100-200 µm) in vitro for 14 days, and then implanted the constructs in intramuscular pockets or 5-mm mandibular defects in nude rats for six weeks [48,49]. As opposite to the study by Braccini et al, the authors did not found significant differences in bone formation between the constructs cultured under static or dynamic conditions, suggesting that other factors couls play a role in enhancing the bone formation ability of these constructs.…”